Si含量对电弧离子镀Ti-Al-Si-N薄膜组织结构和力学性能的影响

EFFECT OF Si CONTENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti-Al-Si-N FILMS DEPOSITED BY CATHODIC VACUUM ARC ION PLATING

利用磁过滤电弧离子镀技术在高速钢基体上制备了不同Si含量的Ti-Al-Si-N薄膜,研究了Si含量对薄膜组织结构以及力学性能的影响.结果表明,Ti-Al-Si-N薄膜主要由晶态TiAlN和非晶态的Si_3N_4组成,随着Si含量的增加,XRD衍射峰强度减弱,晶粒尺寸减小;薄膜的显微组织也由明显的柱状晶转变为致密的纳米晶结构.利用纳米硬度仪对薄膜的硬度和弹性模量进行了分析,结果表明,薄膜的硬度和弹性模量有着相似的变化趋势,随着Si含量的增加,两者都先增加,当Si含量达到一定程度时.它们会逐渐稳定在一定范围内,而后又随Si含量的继续增加呈下降趋势.通过划痕测试对薄膜结合强度进行了分析,结果表明,薄膜与基体的结合强度随Si含量的增加先减小而后增加.

Nanocomposite films deposited by physical vapor deposition （PVD） methods have been attracting much attention worldwide in the last decade. Among these, Ti-Al-N is one of the most thoroughly studied hard film materials. Compared with such films as Ti-N, Ti-C-N and Ti- Zr-N, Ti-A1-N films are commercially available for various machining applications, due to their high hardness, relatively low friction coefficient, good oxidation and corrosion resistance. However, under certain conditions the loose of hardness and oxidation, the high internal stress are still serious drawbacks and restrict their industrial applications. Therefore, seeking for a new kind of film on basis of Ti-Al-N films becomes necessary, it is significant to study the microstructure and properties of the films aim at specific application. In the present work, Ti-Al-Si-N films with various silicon contents were deposited on high speed steel substrates with the assistance of cathodic vacuum arc ion plating （AIP）. The film structure, chemical and phase composition, mechanical and tribological properties are characterized by XPS, XRD, SEM, TEM, nano-indentation and Rockwell indenter. Combined with XRD and XPS analysis, the results indicated that the films were composed of crystalline TiAlN and amorphous Si3N4. With increasing silicon content in the film, a deterioration of the preferred orientation and a reduction of the grain size were detected. SEM observation of the film cross-sections showed that the microstructure changed from obvious columnar to dense nano-structure. Furthermore, with increasing silicon content, both the hardness and elastic modulus firstly increased a lot, within a certain ranges of silicon content changed to be steady, and then sharply decreased with more silicon addition in the film. The H3/E2 ratio can be obtained on basis of measurements of hardness H and Young＇s modulus E, it is proportional to the film resistance to plastic deformation. The results showed that the harder the film is, the higher the resistance to plastic deformation is in films. The adhesive strength between substrate and films was also studied by scratch tests, the values decreased firstly, and then increased again with increasing silicon content. The essence of above phenomena is attributed to the variations of microstructure and morphologies in the films induced by increasing silicon content. This whole study implies that these Si-doped Ti-Al-N films deserve some cautiousness before its application for wear resistance.